AK4648 Datasheet, PDF (56/119 Pages) Asahi Kasei Microsystems – Stereo CODEC with MIC/HP/SPK-AMP

[AK4648]
■ De-emphasis Filter
The AK4648 includes the digital de-emphasis filter (tc = 50/15μs) by IIR filter. Setting the DEM1-0 bits enables the
de-emphasis filter (Table 36).
DEM1
0
0
1
1
DEM0
Mode
0
44.1kHz
1
OFF
0
48kHz
1
32kHz
Table 36. De-emphasis Control
(default)
■ 5 Band Equalizer
The AK4648 has 5 Band Equalizer on DAC block. The center frequencies and cut/boost amount are selected by
FBEQx3-0 bits (Table 37).
• Center frequency: 100Hz, 250Hz, 1kHz, 3.5kHz, and 10kHz (Note 56, Note 57)
• Cut/Boost amount: Minimum –10.5dB, Maximum +12dB, Step 1.5dB
Note 56: These are the frequencies when the sampling frequency is 44.1kHz. These frequencies are proportional to the
sampling frequency.
Note 57: 100Hz is not center frequency but the frequency component lower than 100Hz is controlled.
Note 58: 10kHz is not center frequency but the frequency component higher than 10kHz is controlled.
FBEQ bit controls ON/OFF of this Equalizer.
FBEQA3-0: Select the boost level of 100Hz
FBEQB3-0: Select the boost level of 250Hz
FBEQC3-0: Select the boost level of 1kHz
FBEQD3-0: Select the boost level of 3.5kHz
FBEQE3-0: Select the boost level of 10kHz
FBEQx3-0 Boost amount
0H
+12.0dB
1H
+10.5dB
2H
+9.0dB
3H
+7.5dB
:
:
8H
0dB
(default)
:
:
DH
−7.5dB
EH
−9.0dB
FH
−10.5dB
Table 37. Boost amount of 5 Band Equalizer
MS0625-E-01
- 56 -
2007/06